I got an authentic DMAX wing, it attaches to the hatch through two self tapping screws. You CAN 3M double sided tape the wing, but it may fall off. But to answer your question YES it bolts up to the Metal and not the Glass.

And no, it does not come with hardware. It appears that you have the freedom to mount it which way you think is best. Some people dont want to use bolts, some dont want to use 3M. Either will work though.